docker: Got permission denied while trying to connect to the Docker daemon socket at unix:///var/run

使用docker时出现以下错误：

docker: Got permission denied while trying to connect to the Docker daemon socket at unix:///var/run/docker.sock: Post http://%2Fvar%2Frun%2Fdocker.sock/v1.29/containers/create: dial unix /var/run/docker.sock: connect: permission denied.

解决办法：

在命令前加sudo或者切换到root用户。